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"I think in some ways we owed it to the industry to try new things," said Sean McManus, president of CBS News. "But we found at 6:30 with only 22 minutes of programming time, people basically want you to tell them what happened in the world that day . . . That's probably the biggest lesson we learned."

Which raises an important question: Six months into Couric's tenure at the Tiffany Network, what else have we learned?

Lesson 1: A big name can't do it all.

In hiring Couric, CBS gambled about $15-million annually that her superstar status could upset the network news applecart and draw legions of new viewers to the time slot.

Indeed, the week she debuted, the Evening News drew a first-place average of 10.1-million viewers, according to Nielsen Media Research.

But a month later, the network's newscast was back to third place, drawing 8.3-million viewers, behind Gibson, who had a lower profile with better hard news anchor credentials when he took over ABC's World News in May.

"Charlie Gibson was not a superstar," said Robert Thompson, head of the Center for the Study of Popular Television at Syracuse University. "Katie Couric had to bring to her transition all the baggage that was the Katie Couric Story. Moving into . . . the serious part of news broadcasting is really hard to do when you're a superstar."

Lesson 2: Reinventing the evening news is tougher than it looks.

Couric debuted with hope she could revamp the network news model, with newsmaker interviews and a new "Free Speech" commentary segment featuring everyone from Super Size Me director Morgan Spurlock to conservative radio star Rush Limbaugh.

Six months later, "Free Speech" is gone, and Couric's evening news looks a lot more like her competitors' broadcasts - though with more feature stories, more health stories and more stories with the lead anchor as reporter, according to data on analyst Andrew Tyndall's Web site.

"The network news is a reporter and producer's medium, not an anchor's medium," said Tyndall, a New York media analyst who claims to have seen every weekday network news broadcast since 1987.

Lesson 3: Charisma won't help much.

With about 20 minutes of "news hole" each day in a show with decades of tradition, Couric doesn't have much room to deploy her biggest weapon: her personality. It's quite a change from her morning television days, where the stories often are as much as about the anchors as anything else.

"(CBS) tried to shape the newscast to the anchor . . . but what they found out is more often you have to shape the anchor to fit the (broadcast)," said Terry Martin, a professor at Quinnipiac University who worked at CBS News for 34 years. "To try to significantly change the formula (while) expecting to see a return on your investment right away - I'm not sure that's possible."

Lesson 4: Gender may matter after all.

Martin noted that Couric's highly visible, occasionally bumpy transition to the evening news - including snarky comments about how her eyebrows seem to arch higher with each passing month - stands in stark contrast to Gibson's rise from Good Morning America straight man to contender for bragging rights as highest-rated evening news anchor.

Even while noting that Gibson took over a second place newscast and came to World News with loads of experience subbing in the evening, McManus agreed that some viewers - and reviewers - also may be reacting to Couric's gender.

"She has been under enormous scrutiny for a lot of things that have nothing to do with covering the news, whether it's her hair or her clothes or whatever," said McManus. "I've said all along, people can be as critical as they want, but they should judge her on her performance as an anchor and an interviewer."

Lesson 5: The evening news and its anchors are here to stay awhile.

Yes, fewer people watch the evening news than in previous years.

But on the week of Feb. 19, an average 25-million people still watched the three evening newscasts each day - an audience far larger than those drawn by cable TV or most Web sites. McManus predicted that as Couric gets more chances to cover big stories, her stock will rise with more traditional news viewers.

"It is one of the great conundrums that we deal with; many of the elements that we find most appealing about Katie are difficult to get into a 20-minute newscast," he said. "She does deliver the news in a less formal way. I think, over time, people will appreciate it."

And during moments of calamity or big news, it's hard to equal the emotional impact of a reassuring news anchor.

"There's something special about having a person on-screen with human emotions telling you what's going on," said Kimberly Meltzer, an assistant journalism professor at Lehigh University, who once worked briefly for Couric on the Today show. "This human rapport is a special kind of relationship; it's not going to disappear overnight."

Eric Deggans can be reached at deggans@sptimes.com or (727) 893-8521. See his blog at blogs.tampabay.com/media.